The present invention refers to an apparatus for simulating the ambient color and translucence conditions present in the oral cavity of a patient for the purpose of checking the color stimulus specification of dentures prior to their implanting into the oral cavity of the patient. Moreover, the invention refers, according to a second aspect, to a method for checking the color stimulus specification of a denture.
During the manufacture of dentures, be these crowns, bridges, laminates etc., the problem arises of exactly matching the color of the denture with the color of adjacent teeth. In the meantime, the possibility exists to exactly determine the color of teeth, particularly the color of teeth adjacent to a denture to be implanted. For this purpose, for example a method and an apparatus as disclosed in U.S. Pat. No. 6,038,024 can be adopted; there, a method and an apparatus is described for exactly determining the color stimulus specification of translucent objects, for example teeth and dentures.
However, a problem still remains as far as the quality control during the manufacture of a denture is concerned. Usually, a denture is manufactured by a dental technician in his laboratory. Prior to sending the denture to the dentist who will implant the denture into the oral cavity of the patient, the dental technician should be in a position to check the denture as far as its color, particularly its color stimulus specification, is concerned. Nowadays, such a check is possible only with the help of an existing prefabricated tooth sample, a so-called color key. Thus, in the laboratory of the dental technician, i.e. in the absence of the oral cavity of the patient, it is not possible to perform a direct comparison between the color stimulus of the denture and of the remaining natural teeth of the patient. A possible color mismatch, caused by an erroneous selection of the color key or by a misinterpretation thereof, is recognized only when the dentist implants the denture in the oral cavity of the patient. Of course, this is an absolutely unsatisfactory situation.
Even if the dental technician is in the possession of an apparatus according to U.S. Pat. No. 6,038,024 or a similar apparatus, the denture cannot be checked reliably as far as its color stimulus specification is concerned, since an isolated denture, without the ambience of gum and adjacent teeth, has a different appearance than if it is implanted in the oral cavity of a patient. As soon as the denture is implanted in the oral cavity of the patient, a possible color deviation can be reliably determined if a suitable measuring apparatus is used, but outside of the oral cavity, different, predominantly erroneous measuring results are obtained. The main reason probably is the translucent nature of the tooth material and the color temperature within the oral cavity mainly influenced by the color of the gum; in other words, the ambience greatly influences the color stimulus of a denture.
Thus, since the color of a denture appears correctly only when at least provisionally inserted into the oral cavity of a patient, ideally, the dental technician had to insert the denture first into the oral cavity of the patient to consider whether or not the color still has to be corrected or not; it is understood that, in practice, this is hardly possible.
Therefore, it is an object of the invention to provide an apparatus for simulating the ambient color and translucence conditions present in the oral cavity of a patient for the purpose of checking the color stimulus specification of dentures prior to their implanting into the oral cavity of the patient, thus enabling the manufacturer of a denture to evaluate the color stimulus specification of a denture under most realistic conditions.
To meet this and other objects, the present invention provides an apparatus for simulating the ambient color and translucence conditions present in the oral cavity of a patient for the purpose of checking the color stimulus specification of dentures prior to their implanting into the oral cavity of the patient that comprises means for optically simulating body tissue portions and means for optically simulating at least individual teeth. Preferably, the apparatus comprises an artificial jaw portion including a dimensionally stable, elastic artificial gum body portion simulating at least the vestibulary gum of a patient. The means for optically simulating at least individual teeth is inserted into the artificial gum body portion. The artificial gum body portion preferably consists of a translucent material. The means for optically simulating at least individual teeth are individually removable from the artificial gum body portion and replaceable by a denture.
By means of such an apparatus, for the first time, the ambience of the oral cavity of a patient can be simulated as far as color and translucence are concerned to such an extent that the appearance of a denture can be reliably evaluated prior to implanting it into the oral cavity of a patient.
According to another aspect, the invention also provides a method for checking the color stimulus specification of a denture. According to this method, first, the color stimulus specification of a tooth to be replaced or of an adjacent tooth in the oral cavity of a patient is determined and the measured color stimulus specification value is stored as a desired set value. Then, a denture is manufactured, having a color stimulus specification corresponding to that desired set value. This denture is thereafter inserted into an apparatus for simulating the ambient color and translucence conditions present in the oral cavity of a patient for the purpose of checking the color stimulus specification of dentures prior to their implanting into the oral cavity of a patient, as described herein above, and the color stimulus specification of the denture inserted into that simulation apparatus is determined and the measured color stimulus specification value is stored as actual value. Finally, the stored actual value and the stored desired set value are compared and the color of the denture is corrected, if necessary.